1. Field of the Invention
The present invention relates to communications in networks and, more particularly, to a method for transferring information (station address, multi-cast address) concerning a network interface card (NIC) connected to a switching hub, into the switching hub by receiving and transmitting an information-demanding packet and a recognition packet between the switching hub and the Network Interface Card.
2. Discussion of the Related Art
A conventional method for node recognition will be described with the accompanying drawings.
FIG. 1 is a structural schematic view of a network for describing a conventional method of node recognition, and FIG. 2 is a structural block diagram of the switching hub of FIG. 1.
As described in FIG. 1, a network is composed of a switching hub 11 and a plurality of stations 12 connected to the switching hub 11 for receiving and transmitting data to and from the switching hub 11.
A software 11a for managing a switching hub is in the switching hub 11. Each of the stations 12 includes a network interface card (NIC) 12a for transmitting and receiving data to and from the switching hub 11 and a software driver 12b for managing the NIC 12a.
Referring to FIG. 2, the switching hub 11 is composed of a memory part 11b; a controller 11c for controlling the memory part 11b, the MACS 11d, and the overall operations of the switching hub 11; a plurality of media access controllers (MAC) 11d connected to the controller 11c in parallel; and a plurality of physical layers (PHYs) 11e connected to each of the MACS 11d for making data suitable for communication protocol.
The MAC 11d converts data transmitted from a software driver 12b located in each station 12 into data suitable for Ethernet protocol for transmitting the converted data to the PHYs 11e, and transmits data from the PHY 11e to the software driver 12b. The PHY 11e converts a digital data signal transmitted from the MAC 11d into an electrical data signal, which is transmitted to another station 12 through a cable, and converts the electrical data signal transmitted through a cable into a digital data signal which is transmitted to the MAC 11d.
FIG. 3 is a structural block diagram of the NIC of FIG. 1, which is composed of the PHY 11e for converting an electrical signal transmitted through a cable into a digital data signal, and the MAC 11d for transmitting the digital data signal to the software driver 12b.
FIG. 4 is a structural block diagram of a conventional MAC which is composed of a receiving circuit 12c for receiving a data signal transmitted from the PHY 11e, a first buffer 12d for storing the data signal received by the receiving circuit 12c for a predetermined time, a system interface 12e for interfacing the data signal outputted from the first buffer 12d for making the data signal suitable for system protocol, a second buffer 12f for temporarily storing the data signal outputted from the system interface 12e, and a transmitting circuit 12g for transmitting the data signal stored in the second buffer 12f to the PHY 11e.
Since, in the network, the switching hub 11 selectively relays data, the switching hub 11 has to know the address and other information of each station 12 having an NIC 12a therein.
The communication process between the switching hub 11 and the NIC 12a in each station 12 will be described below.
First, the switching hub 11 prepares an information table for each station 12 and transmits data to a station 12 although the switching hub 11 may have no information regarding the station 12 it transmits to. For example, a station that the switching hub 11 has no information about would be a newly added station. If a station is newly added, the switching hub 11 does not recognize the new station address and cannot form an information table for the new station. Accordingly, the switching hub 11 unnecessarily transmits data to the new station 12 that it has no information about, because the switching hub 11 cannot determine whether the new station 12 actually wants to receive data.
Since the switching hub 11 transmits all data into newly-added stations, the newly-added stations have relatively heavy data traffic. If a packet is sent into the switching hub 11 from the newly-added station 12 which has received all the data transmitted from the switching hub 11, the switching hub 11 then analyzes the packet so as to form an information table. Once the information table has been formed, the switching hub 11 transmits data into the stations 12 according to the information table.
FIG. 5 shows a packet transmitted from the switching hub 11 to each station 12. All data are transmitted in the unit of packets. First, a source address (SA) and then a destination address (DA) are successively recorded in the packet. Thereafter, the size and form of the data are recorded. Subsequently, the packet in which the foregoing information is recorded is transmitted from the switching hub 11 to each station 12, and from each station 12 back to the switching hub 11. Accordingly, if a station is newly added, the packet does not indicate whether the new station wants to receive data.
A conventional method for node recognition has the following problems.
First, until a data is sent from a newly-added station, a switching hub cannot form an information table, thereby increasing data traffic of the newly-added station.
Second, if two or more stations are newly added, traffic of the entire network becomes heavier in case of employing a multi-cast technique, although data are sent from the newly-added stations so that the switching hub forms information tables.